The following is provided as background information only and should not be taken as an admission that any subject matter discussed or that any reference mentioned is prior art to the instant invention. All publications and patent applications herein are incorporated by reference to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference.
In multi-cellular organisms, communication between individual cells is essential for the regulation of complex biological processes such as growth, differentiation, motility and survival. Receptor tyrosine kinases are among the primary mediators of signals between the surface of the cell to target proteins in cytoplasmic compartments and in the nucleus. One family of receptor tyrosine kinases, the epidermal growth factor receptors (EGFRs), has been shown to have a critical role in these signal transduction processes.
Members of the epidermal growth factor receptor family (EGFR/ErbB1/HER1, ErbB2/HER2, ErbB3/HER3, and ErbB4/HER4) are transmembrane tyrosine kinases that are activated by ligand-induced dimerization. (Schreiber et al., (1983) Journal of Biological Chemistry 258(2):846-53.; Ushiro and Cohen, (1980) Journal of Biological Chemistry 255(18):8363-5.). These receptors regulate cell proliferation, differentiation, and migration, and their abnormal activation is associated with a variety of human cancers. (Yarden and Sliwkowski, (2001) Nature Reviews Molecular Cellular Biology 2(2):127-37). Several cancer drugs (for example, Erlotinib) interact with the ATP-binding site of the EGFR kinase to halt tumor growth and increase apoptosis in cancer cells.
It is known that the EGFR kinase domain is activated after ligand-induced dimerization of the extracellular region of the receptor, although the underlying mechanism has remained elusive. Studies have shown that mutations in the catalytic domain of EGFR can interfere with the kinase activity of these proteins. (Chan et al., (1996) Journal of Biological Chemistry, Vol. 27(37): 22619-23.).
The development of compounds that directly inhibit the kinase activity of the EGFR, as well as antibodies that reduce EGFR kinase activity by blocking EGFR activation, are areas of intense research effort (de Bono and Rowinsky, (2002) Trends in Molecular Medicine, Vol. 8 (4 Suppl): S19-26; Dancey and Sausville, (2003) Nature Reviews. Drug Discovery, Vol. 2: 296-313.). Several studies have demonstrated or suggested that some EGFR kinase inhibitors might improve tumor cell or neoplasia killing when used in combination with certain other anti-cancer or chemotherapeutic agents or treatments (e.g. Herbst et al., (2002) Expert Opinion on Biological Therapy, Vol. 1(4): 719-32; Solomon et al., (2003) International Journal Radiology, Oncology, Biology, Physics, Vol. 57(1): 713-23; Krishnan et al., (2003) Frontiers in Bioscience, Vol. 8: e1-13; Grunwald and Hidalgo, (2003) Journal of the National Cancer Institute, Vol. 95: 851-67; Seymour, (2003) Current Opinion in Investigational Drugs, Vol. 4(6): 658-66; Khalil et al., (2003) Expert Review on Anticancer Therapy, Vol. 3(3): 367-80; Bulgaru et al., (2003) Expert Review on Anticancer Therapy, Vol. 3(3): 269-79; Ciardiello et al., (2000) Clinical Cancer Research, Vol. 6: 2053-63; and Patent Publication No: US 2003/0157104).
The Mig-6 protein has been shown to be a negative modulator of EGFR activity. Ullrich et al (WO 02/067975) described using the protein to inhibit EGFR activity in rat fibroblasts. The interaction between EGFR and Mig-6 was determined using a yeast two hybrid screen. A similar method was used to screen for other potential modulators of EGFR. However, the high rate of false negatives inherent to a yeast two hybrid screen makes such a process inefficient for most drug discovery uses.
Drugs targeting EGFR that are currently in use inhibit EGFR through interaction with the active site, but such pharmaceuticals are not effective for many EGFR-related illnesses.
A need exists, therefore, for methods and compositions capable of modulating the activation of EGFR at sites other than the active site.